A body of mass 2 kg moves under a force of $( 2 \hat { \mathrm { i } } + 3 \hat { \mathrm { j } } + 5 \widehat { \mathrm { k } } ) \mathrm { N }$. It starts from rest and was at the origin initially. After 4 s, its new coordinates are $( 8 , b , 20 )$. The value of $b$ is $\_\_\_\_$.\\
(Round off to the Nearest Integer)